It is common practice to construct parking garages by use of many precast concrete portions. This permits a considerable portion of the garage to be manufactured at one central location from whence the precast portions can be shipped to the building site and erected with a minimum of time at the site. This technique especially is appropriate for a parking garage because the slabs which form both the ceiling and the floor of adjacent vertical levels are well adapted to being cast in one location and shipped to another. Concrete slabs have been improved to the point where they are strong enough to extend from a center file of columns completely to an outer file of columns ("full-span slabs") so that the number of individual garage components has been decreased.
Parking garages typically are constructed by erecting a plurality of vertically extending columns and interconnecting the columns by horizontally extending beams (or spandrels). Thereafter, rectangular precast slabs are placed atop the beams to interconnect the columns and form the various parking levels.
One of the drawbacks of the foregoing construction is that a substantial number of components are required to construct a garage. Assuming the conventional practice of providing two files of exterior columns and one file of interior columns, the slabs must extend from each side of the interior file of columns to both exterior files of columns. Because the slabs usually are inclined to provide ramps by which vehicles may ascend and descend, spandrels having an opposite slope must be disposed on either side of the interior file of columns. Accordingly, not only must spandrels extend between adjacent exterior columns to support one end of the slabs, but two spandrels must extend between adjacent interior columns. This requirement increases the number of garage components. Also, because the interior columns must support two spandrels instead of one, the interior columns must be considerably stronger than the exterior columns and this in turn increases the expense of the garage.
Another drawback of conventional parking garage construction is that additional structure is required to prevent cars from being driven over the outermost edge of the slabs. Although curbs can be molded into the slabs or can be provided separately, it still is necessary for adequate safety to extend cables, guardrails, or safety walls between adjacent columns. This approach is unsightly, and to improve the appearance of the external portion of the parking garage, so-called curtain walls or other facades usually are attached to the columns. The curtain walls are expensive and installation is time-consuming.
A parking garage construction is known in which the spandrels extending between interior columns no longer are needed. This is brought about by spacing the columns close together and resting the slabs directly on outwardly projecting portions (haunches) included as part of the columns. Although this construction eliminates the spandrels extending between interior columns and thus provides a garage having fewer components and lighter-weight interior columns, it still fails to solve other prior art concerns such as the need for safety walls, guardrails, curtain walls, and so forth.
In general, it is a major concern in constructing a parking garage to construct the garage with the fewest possible components and to precast as many of those components as possible, while at the same time creating an aesthetically pleasing structure. Although certain advances have been made, still additional improvements are possible.